The present invention is directed to apparatus and methods for interconnecting a main air handling system with a subsystem.
In U.S. Pat. No. 4,249,758, Harris discloses an apparatus and method for interconnecting duct work with a heating system main component, utilizing a connecting member formed of molded fiberglass, plastic or similar material and which connecting member has an enlarged circumferential end face generally perpendicular to the elongated direction of the tube which forms the connecting member. A gasket is attached to the face with an adhesive outer surface, and with a piece of release paper over the adhesive. As described in the Harris patent, the passageway of the tubular connecting member is then matched up with an opening in an air system main component so that the gasket surrounds the opening, which is then pushed into sealing relationship with the main component. In the arrangement taught by Harris, the air passing through the opening in the main component and into the tubular connecting member passes directly across the gasket; that is, the gasket is exposed to the air stream. If the temperature of the heated air is sufficiently high, there is a potential fire risk, since many of the materials used for the gasket are flammable. Further, prolonged passage of heated air across the exposed portion of the gasket can cause deterioration.
U.S. Pat. No. 3,985,158 to Felter discloses a box of a plastic insulating material having flanges which are utilized for attachment to a supporting structure. Netherlands Patent 76,439 discloses a tubular connecting member configuration quite similar to that of the Harris patent, with an annular gasket surrounding and sealing a plurality of individual tubular members.
British Patent 1,193,748 is also quite similar in construction to the arrangement taught by Harris, disclosing a pipe connection having a sealing ring used for joinder in the opening of a connecting air diffusive box.